DEAR CAROLYN: My mother moved to be closer to us when we had a baby, who’s now 2. She’s not responsible with him. She gives him anything he points to and grunts. Just in the past month, this has included a lighter (“He doesn’t know how to use it”), garden shears, the lime from her rum-and-coke, soda, hard mints, the hose, and anything else that catches his eye.

I know his company is the bright spot in her otherwise lonely, depressed days but I am more exhausted after bringing him to her than I am just watching him myself.

I have to constantly say “no” to the toddler AND to the mother who is just as impulsive. I have to repeat myself to the point of frustration to get her to follow basic rules about health/safety and spoiling.

She claims she should be able to spoil him since she’s the grandmother and she doesn’t get to see him much — she sees him at least once a week. Cutting off contact isn’t right, but I have another on the way, and the thought of dealing with all three of them makes me want to cry.

How do you teach someone to be a smart, careful person?

Exasperated Mom to Two Toddlers

DEAR EXASPERATED: Coincidentally, I had three actual toddlers for a while myself, and the best advice I can give you is to expect from them exactly what they’ve proven they’re capable of giving. By that I mean, expect your two toddlers to be impulsive, self-absorbed, moody, capable of following only the simplest instructions, and occasionally so frustrating that you want to scream.

That doesn’t change just because one of your toddlers is over 50.

In fact, at difficult times like this, it’s often hoping for better that is the enemy of contentment. If you go into visits expecting a break — and hold out hope that your mother will aha-moment her way to grasping that one doesn’t give a lighter to a 2-year-old (that might be a new high point of some kind, by the way) — then you will be disappointed and frustrated on a regular basis.

If instead you go into it expecting your mother to hand your child enough destructive objects to supply a remake of “The Gashlycrumb Tinies,” then you’ll know you’re on duty and pre-empt any disappointment.

Maybe reframing is having more of a moment than it deserves right now, but try it; there really is something to it.

It’s also OK to give up on fixing this yourself and to let time fix it for you eventually.

While your kids are little-little, they need extra supervision. That’s just a fact of parental life. Parents can do things on the margins to make things easier, like childproof the house and hire baby sitters for respite care, but you’re still on little-kid duty until your kids develop some judgment.

The only thing different in your scenario is that your “help” doesn’t help. It’s OK to tweak this on the margins, too — say, move your visits with this grandma to child-friendly places like play gyms or children’s museums — and wait for your kids’ eventual maturity to solve it.

Last thing, keep an eye out for possible cognitive decline. Seriously — a lighter.

Adapted from a recent online discussion. Email Carolyn at tellme@washpost.com, follow her on Facebook at www.facebook.com/carolyn.hax or chat with her online at noon Eastern time each Friday at www.washingtonpost.com.